McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 4 9 Drugs used to treat anaemias

AGENTS USED FOR OTHER ANAEMIAS This section discusses treatment for megaloblastic anaemias and sickle cell anaemia. Table 49.3 gives a complete list of agents. A gents for megaloblastic anaemias Megaloblastic anaemia is treated with folic acid and vitamin B 12 . Folate deficiencies usually occur secondary to increased demand (as in pregnancy or growth spurts); as a result of absorption problems in the small intestine; because of drugs that cause folate deficiencies; or sec- ondary to the malnutrition of alcoholism. Vitamin B 12 deficiencies can result from poor diet or increased demand, but the usual cause is lack of intrinsic factor in the stomach, which is necessary for absorption. The drugs are usually given together to ensure that the problem is addressed and the blood cells can be formed properly (see Table 49.3). Folic acid derivatives include folic acid ( Fefol ) and calcium folinate ( Leucovorin ) . B 12 includes hydroxocobalamin ( Hydroxo-B 12 , Neo-B 12 ), co-methylcobalamin ( Methylcobalamin ) and cyanoco- balamin (generic) . Therapeutic actions and indications Folic acid and vitamin B 12 are essential for cell growth and division and for the production of a strong stroma

Evaluation

■■ Iron products are used to replace iron in cases of iron-deficiency anaemia, which can occur because of deficient iron intake or because of blood loss leading to lower iron levels. ■■ Iron products commonly cause constipation, nausea, green stools and GI upset. ■■ Iron toxicity can cause severe CNS toxicity, coma and even death because high iron levels are very toxic to nerve cell membranes. ■ ■ Monitor response to the drug (alleviation of anaemia). ■ ■ Monitor for adverse effects (GI upset and reaction, CNS toxicity, coma). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. ■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for and specific measures to avoid them; person understands the importance of continued follow-up).

KEY POINTS

TABLE 49.3

DRUGS IN FOCUS Agents used for other anaemias

Drug name

Dosage/route

Usual indications

Agents for megaloblastic anaemias Folic acid derivatives calcium folinate (Leucovorin)

1 mg/day IM for replacement; 12–15 g/m 2 PO, then 10 g/m 2 PO q 6 hours for 72 hours for rescue

Replacement therapy and treatment of megaloblastic anaemia; used as

“leucovorin rescue” after chemotherapy, allowing non-cancerous cells to survive the chemotherapy; used with fluorouracil for palliative treatment of colorectal cancer (see Chapter 14)

1 mg/day PO, IM, SC or IV

Replacement therapy and treatment of megaloblastic anaemia

folic acid (Ferro-F-tab, FGF)

Vitamin B 12 co-methylcobalamin (Methylcobalamin)

2 mL slow IM

Replacement therapy: treatment of pernicious anaemia

cyanocobalamin (generic)

Adult: 5 mg/day deep IM Neonatal: 1 mg/day IM

Replacement therapy; treatment of megaloblastic anaemia, pernicious anaemia Replacement therapy; treatment of megaloblastic anaemia, pernicious anaemia

250–1000 mcg IM alternate days × 1–2 weeks, then 250 mcg/week IM

hydroxocobalamin (Hydroxo-B12,

Neo-B12)

Agent for sickle cell anaemia hydroxyurea (Hydrea)

Initially 15 mg/kg per day PO as a single dose; increase by 5 mg/kg per day every 12 weeks to a maximum dose of 35 mg/kg per day PO

Reduction of frequency of painful crises and to decrease the need for blood transfusions in adults with sickle cell anaemia